In video systems video/image scaling often creates problems, particularly for systems with interlaced video and multiple channel video/image with sub-sampled components such as, for example, chrominance components.
Additionally, an input video source may support formats with image sizes different from an associated output video device. For example, an input source may be a broadcasting station, and the output video devices may be any one of the many available televisions and monitors available to consumers with different sizes and standards. As a result, for example, smaller images need to be scaled properly to fit the size of the display, since consumers would not want to see an image in a corner of a display device.
Scaling multiple channel or interlaced video/image may create problems when trying to properly align different channel at the correct relative spatial positions. One of the most common image formats is the YCrCb format, where there is a luminance Y component and the chrominance Cr and Cb components. Often, the YCrCb components are encoded in a 4:2:0 format where there is only half as much Cr and Cb components as there are Y components. Also, the Cr and Cb components are not placed on the exact pixel locations; instead, the chrominance components are located at half pixel offsets from the Y components. Simple scaling with such formats results in incorrect alignment, which in turn results in incorrect alignment, which in turn results artifacts and significant degradation of the image quality. This becomes even more problematic when images are in YCrCb 4:2:0 interlaced format.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.